Bendix Commercial Vehicle Systems AD-SP SYSTEM PURGE AIR DRYER 10/04 - Manual (Page 19)

19
AD-SP ™ AIR DRYER TROUBLESHOOTING CHART (Continued)
SYMPTOMS CAUSE REMEDY
NOTE: Duty Cycle is the
ratio of time the compressor
spends building air to total
engine running time. Air
compressors are designed
to build air (run “loaded”) up
to 25% of the time. Higher
duty cycles cause
conditions that affect air
brake charging system
performance which may
require additional
maintenance. Factors that
add to the duty cycle are: air
suspension, additional air
accessories, use of an
undersized compressor,
frequent stops, excessive
leakage from fittings,
connections, lines,
chambers or valves, etc. Charge Cycle Time - The AD-SP ™ air dryer is
designed to provide clean, dry air for the brake
system. When a vehicle’s air system is used to
operate non-brake air accessories it is
necessary to determine that; during normal,
daily operation the compressor should recover
from governor “cut-in” to governor “cut-out”
(usually 100 psi to 120 psi) in 90 seconds or
less at engine RPM’s commensurate with the
vehicle vocation. If the recovery time consistently
exceeds this limit, it may be necessary to
“bypass” the air accessory responsible for the
high air usage. An example of where a by-pass
system would be required is when the
compressor is used to pressurize a tank trailer
for purposes of off-loading product. Consult your
local authorized Bendix parts outlet or sales
representative for additional information.
Purge Cycle Time - During normal vehicle
operation, the air compressor must remain
unloaded for a minimum of 30 seconds. This
minimum purge time is required to ensure
complete regeneration of the desiccant material.
If the purge time is consistently less than the
minimum, an accessory by-pass system must
be installed. Consult your local authorized
Bendix parts outlet or sales representative for
additional information.
Air Compressor Size - Although the AD-SP ™ air
dryer can be used in conjunction with larger
compressors, it was designed primarily for units
rated for up to 30 CFM. It is recommended that
when using the AD-SP
™ air dryer with a
compressor which has a rated displacement
exceeding 30 CFM that an authorized Bendix
parts outlet or Bendix marketing representative
be contacted for assistance.
F. Restricted discharge line. See Appendix A, Table
A, column 1 & 2 for recommended sizes. If
discharge line is restricted or more than 1/16"
carbon build up is found, replace the discharge
line. Replace as necessary.
Discharge Line Freeze-Up: The discharge line must
maintain a constant slope down from the
compressor to the air dryer inlet fitting to avoid low
points where ice may form and block the flow. If,
instead, ice blockages occur at the air dryer inlet,
insulation may be added here, or if the inlet fitting is
a typical 90 degree fitting, it may be changed to a
straight or 45 degree fitting. For more information on
how to help prevent discharge line freeze-ups, see
Bendix Bulletins TCH-08-21 and TCH-08-22. Shorter
discharge line lengths or insulation may be required
in cold climates.
F. Air compressor
discharge and/or air
dryer inlet temperature
too high.